In heavy duty foodservice ovens and food vending machines, cleaning is a major consideration. This is particularly important in air recirculating impingement ovens of the type disclosed in U.S. Pat. No. 3,884,213 and in convection ovens with microwave food heating.
U.S. Pat. No. 3,884,213 discloses an oven equipped with a pivotally mounted, rectangular shaped, microwave transparent plate having spaced tubes extending therethrough for forming collimated jets of air that are projected to impinge upon surfaces of a food product. While the disclosed oven provided significant improvements in the transfer of heat to the food product, it was difficult to clean and maintain. Further, the shape and mounting for the jet plate did not permit optimum air flow to provide maximum efficiency and required that the jet plate be microwave transparent.
Vending machines for dispensing hot and cold drinks, candy, cookies, potato chips and other snack foods have enjoyed significant commercial success. However, vending machines for dispensing meals have been limited to dispensers of refrigerated foods such as sandwiches, salads and the like.
Devices heretofore devised for incorporating electronic ovens in food vending machines are disclosed in U.S. Pat. No. 3,333,666; U.S. Pat. No. 3,343,479; U.S. Pat. No. 3,386,550; U.S. Pat. No. 3,397,817; U.S. Pat. No. 3,534,676; U.S. Pat. No. 4,004,712; U.S. Pat. No. 4,398,651; U.S. Pat. No. 4,592,485; U.S. Pat. No. 4,762,250; U.S. Pat. No. 4,783,582 and U.S. Pat. No. 4,784,292.
Vending machines for hot meals generally include a refrigerated compartment for preserving food, a microwave oven compartment for fast cooking, and a conveyor for transferring food from the refrigerated compartment into the microwave oven. However, since vending machines for hot foods have enjoyed very limited commercial success, separate microwave ovens for heating food items removed from a refrigerator are commonly employed in convenience stores, airports, cafeterias and other food vending operations.
Microwave heating of certain foods, including pizza and sandwiches that contain dough and bakery products, typically leaves the surface too moist and less palatable than similar food products cooked in other types of ovens.
Ovens of the type disclosed in U.S. Pat. No. 3,884,213; U.S. Pat. No. 4,154,861; U.S. Pat. No. 4,289,792; U.S. Pat. No. 4,409,453 and U.S. Pat. No. 4,835,351 employ air jets which impinge upon the surface of a food product to provide surface heating of the product in combination with microwave heating. Jet impingement ovens have enjoyed significant success in commercial food service and commercial food processing operations. However, a long felt need exists for apparatus for quickly and efficiently heating food products that require little or no preparation for use in a vending machine for hot meals and in counter top ovens for foodservice operations that are easily cleaned.